Wireless communication systems are widely deployed to provide, for example, a broad range of voice and data-related services. Typical wireless communication systems include multiple-access communication networks that allow users to share common network resources. Examples of such networks are time division multiple access (“TDMA”) systems, code division multiple access (“CDMA”) systems, single carrier frequency, division multiple access (“SC-FDMA”) systems, orthogonal frequency division multiple access (“OFDMA”) systems, and other like systems. An OFDMA system is supported by various technology standards such as evolved universal terrestrial radio access (“E-UTRA”), Wi-Fi, worldwide interoperability for microwave access (“WiMAX”), ultra mobile broadband (“UMB”), and other similar systems. Further, the implementations of these systems are described by specifications developed by various industry standards bodies such as the third generation partnership project (“3GPP”) and 3GPP2.
As wireless commutation systems evolve, more advanced network equipment is introduced that provide improved features, functionality, and performance. A representation of such advanced network equipment may also be referred to as long-term evolution (“LTE”) equipment or long-term evolution advanced (“LTE-A”) equipment. LTE is the next step in the evolution of high-speed packet access (“HSPA”) with higher average and peak data throughput rates, lower latency, and a better user experience especially in high-demand geographic areas. LTE accomplishes this higher performance with the use of broader spectrum bandwidth, OFDMA and SC-FDMA air interfaces, and advanced antenna methods.
Communications between wireless devices and base stations may be established using single-input, single-output systems (“SISO”), where only one antenna is used for both the receiver and transmitter; single-input, multiple-output systems (“SIMO”), where multiple antennas are used at the receiver and only one antenna is used at the transmitter; and multiple-input, multiple-output systems (“MIMO”), where multiple antennas are used at the receiver and transmitter. Compared to a SISO system, a SIMO system may provide increased coverage while a MIMO system may provide increased spectral efficiency and higher data throughput if the multiple transmit antennas, multiple receive antennas or both are utilized. Further, uplink (“UL”) communication refers to communication from a wireless device to a base station. Downlink (“DL”) communication refers to communication from a base station to a wireless device.
In 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Physical Channels and Modulation (Release 8), 3GPP, 3GPP TS 36.211 (“LTE Release 8”), the use of a single antenna is supported for UL transmission that employs SC-FDMA. In 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Further Advancements For E-UTRA; Physical Layer Aspects (Release 9), 3GPP, 3GPP TR 36.814 V9.0.0 (March 2010) (“LTE-A Release 10”), multiple antennas may be used to improve UL performance by, for instance, the use of transmit diversity and spatial multiplexing. Various transmit diversity schemes may be used such as space frequency block coding (“SFBC”), space time block coding (“STBC”), frequency switched transmit diversity (“FSTD”), time switched transmit diversity (“TSTD”), pre-coding vector switching (“PVS”), cyclic delay diversity (“CDD”), space code transmit diversity (“SCTD”), orthogonal resource transmission (“ORT”), and other similar approaches.
Skilled artisans will appreciate that elements in the accompanying figures are illustrated for clarity, simplicity and to farther improve understanding of the exemplary embodiments, and have not necessarily been drawn to scale.